26 C.F.R. § 1.702-2
For the purpose of determining a net operating loss deduction under section 172, a partner shall take into account his distributive share of items of income, gain, loss, deduction, or credit of the partnership. The character of any such item shall be determined as if such item were realized directly from the source from which realized by the partnership, or incurred in the same manner as incurred by the partnership. See section 702(b) and paragraph (b) of § 1.702-1 . To the extent necessary to determine the allowance under section 172(d)(4) of the nonbusiness deductions of a partner (arising from both partnership and nonpartnership sources), the partner shall separately take into account his distributive share of the deductions of the partnership which are not attributable to a trade or business and combine such amount with his nonbusiness deductions from nonpartnership sources. Such partner shall also separately take into account his distributive share of the gross income of the partnership not derived from a trade or business and combine such amount with his nonbusiness income from nonpartnership sources. See section 172 and the regulations thereunder.
26 C.F.R. §1.702-2